netdev - [PATCH bpf-next v3 7/9] libbpf: add support for supplying target to bpf_raw_tracepoint

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Message-ID: <159974339713.129227.17759670478076731926.stgit@toke.dk>
Date:   Thu, 10 Sep 2020 15:09:57 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Eelco Chaudron <echaudro@...hat.com>,
        KP Singh <kpsingh@...omium.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [PATCH bpf-next v3 7/9] libbpf: add support for supplying target to
 bpf_raw_tracepoint_open()

From: Toke Høiland-Jørgensen <toke@...hat.com>

This adds support for supplying a target fd and btf ID for the
raw_tracepoint_open() BPF operation, using a new bpf_raw_tracepoint_opts
structure. This can be used for attaching freplace programs to multiple
destinations.

Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
---
 tools/lib/bpf/bpf.c      |   13 ++++++++++++-
 tools/lib/bpf/bpf.h      |    9 +++++++++
 tools/lib/bpf/libbpf.map |    1 +
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 82b983ff6569..25c62993c406 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -804,17 +804,28 @@ int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)
 	return err;
 }
 
-int bpf_raw_tracepoint_open(const char *name, int prog_fd)
+int bpf_raw_tracepoint_open_opts(const char *name, int prog_fd,
+				 struct bpf_raw_tracepoint_opts *opts)
 {
 	union bpf_attr attr;
 
+	if (!OPTS_VALID(opts, bpf_raw_tracepoint_opts))
+		return -EINVAL;
+
 	memset(&attr, 0, sizeof(attr));
 	attr.raw_tracepoint.name = ptr_to_u64(name);
 	attr.raw_tracepoint.prog_fd = prog_fd;
+	attr.raw_tracepoint.tgt_prog_fd = OPTS_GET(opts, tgt_prog_fd, 0);
+	attr.raw_tracepoint.tgt_btf_id = OPTS_GET(opts, tgt_btf_id, 0);
 
 	return sys_bpf(BPF_RAW_TRACEPOINT_OPEN, &attr, sizeof(attr));
 }
 
+int bpf_raw_tracepoint_open(const char *name, int prog_fd)
+{
+	return bpf_raw_tracepoint_open_opts(name, prog_fd, NULL);
+}
+
 int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size,
 		 bool do_log)
 {
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 015d13f25fcc..30e8854374c0 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -233,7 +233,16 @@ LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);
 LIBBPF_API int bpf_prog_query(int target_fd, enum bpf_attach_type type,
 			      __u32 query_flags, __u32 *attach_flags,
 			      __u32 *prog_ids, __u32 *prog_cnt);
+struct bpf_raw_tracepoint_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	int tgt_prog_fd; /* target program to attach to */
+	__u32 tgt_btf_id; /* BTF ID of target function */
+};
+#define bpf_raw_tracepoint_opts__last_field tgt_btf_id
+
 LIBBPF_API int bpf_raw_tracepoint_open(const char *name, int prog_fd);
+LIBBPF_API int bpf_raw_tracepoint_open_opts(const char *name, int prog_fd,
+					    struct bpf_raw_tracepoint_opts *opts);
 LIBBPF_API int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf,
 			    __u32 log_buf_size, bool do_log);
 LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 92ceb48a5ca2..a23d9f3f940c 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -303,6 +303,7 @@ LIBBPF_0.1.0 {
 LIBBPF_0.2.0 {
 	global:
 		bpf_program__section_name;
+		bpf_raw_tracepoint_open_opts;
 		perf_buffer__buffer_cnt;
 		perf_buffer__buffer_fd;
 		perf_buffer__epoll_fd;